Electrical connectors typically include a housing that supports a plurality of electrical contacts that each define a mating end and an opposing mounting terminal. The mating ends define a mating interface configured to mate with a complementary mating interface of an electrical component, which can be another electrical connector or alternative electrical device. The mounting terminals define a mounting interface configured to connect to a substrate, such as a printed circuit board (PCB).
Plated through holes extend from an upper surface of a printed circuit board to an opposite, parallel lower surface of a PCB. Electrical connectors are mounted to the upper surface of the PCB such that electrical press-fit tails of the electrical contacts extend into the plated through holes. A typical press-fit tail 88 is shown in FIG. 3. When the length of a plated through hole exceeds the length of an electrical connector press-fit tail, the plated through hole can be backdrilled from the lower surface of the PCT in order to remove unused plating material in the plated through hole.
Referring to FIG. 3, an electrical contact 85 includes a contact body 86 and a mounting terminal 87 that extends distally from the contact body 86. The mounting terminal 87 defines a press-fit tail 88 that is shaped generally as an eye-of-the-needle (EON) that is configured to compress when inserted into a through hole which can be a plated through hole or via of a printed circuit board. The mounting terminal 87 includes a pair of beams 89 connected at their proximal and distal ends, and a substantially oval-shaped opening 90 that is disposed between the beams 89. The opening 90 defines a width of approximately 0.25 mm and a length of approximately 0.8 mm. The mounting terminal 87 further includes a neck connected between the contact body 86 and the beams 89 having a length of approximately 0.44 mm. The beams 89 define outer sides 91 that define a width therebetween of approximately 0.55 mm.
The mounting terminal 87 defines an overall length of approximately 1.45 mm, a penetration length into the underlying substrate of approximately 1.25 mm, and a stub length SL of approximately 0.58 mm. The stub length of the mounting terminal 87 is the distance between the location where the mounting terminal 87 mates with the inner surface of the via and the distal or free end of the mounting terminal 87. The stub length SL of the mounting terminal 87 can, in some instances, be the same as the through hole stub length, which is the distance between the location where the mounting terminal 87 mates with the inner surface of the via and the end of the via plating. Often, however, the plated through holes are backdrilled so as to remove a quantity of excess plating that extends distal of the location where the mounting terminal 87 mates with the inner surface of the via, thereby reducing the stub capacitance of the plated through hole.